Effects of morphine and met-enkephalin analogue on gastric lesions induced by indomethacin.

The effects of morphine HCl and a synthetic met-enkephalin analogue [D-Ala2,MePhe4,Met(O)5ol]enkephalin (FK 33-824) on gastric damage produced by the intraperitoneal administration of indomethacin (10 mg/kg i.p.) have been investigated. Rats intraperitoneally pretreated with morphine HCl (10 mg/kg i.p.) and FK 33-824 (1 mg/kg i.p.) showed a statistically significant reduction both of the number and intensity of lesions induced by indomethacin. This protection was reversed by naloxone HCl (2 mg/kg i.p.). The protective effect was not related to a reduction of gastric secretion since the antisecretory drug cimetidine (25 mg/kg i.p.) and methscopolamine bromide (10 mg/kg i.p.) did not significantly prevent mucosal damage under the same experimental conditions.